The Northern Ireland Assembly is to meet later for the first time since a crisis over the IRA threatened the power-sharing institutions.

The Democratic Unionists, the largest party at Stormont, had unsuccessfully sought a four-week adjournment after police said members of the Provisional movement shot a man dead in East Belfast.

The DUP has promised it will not be business as usual when Assembly members return from their summer break today. Intensive talks launched by the British and Irish governments are due to begin later this week.

Politicians are due to debate a Sinn Fein motion condemning the murders of former IRA members Jock Davison and Kevin McGuigan, and calling on anyone with information to pass it on to the police.

Police have insisted the IRA is not back on a war footing but the disclosure that the organisation still exists has rocked an already badly-divided political establishment.

The British Government has decided to legislate on welfare reform in Northern Ireland if the Stormont parties cannot reach agreement.

The Democratic Unionists and Sinn Fein have been at loggerheads over the issue for months and the devolved administration in Belfast has been plunged into financial peril.

The talks are planned for this week at Stormont House with Secretary of State Theresa Villiers representing London and Foreign Affairs Minister Charlie Flanagan, Dublin.

The purpose is to secure full implementation of the Agreement and to deal with issues arising from the impact of continued paramilitary activity in Northern Ireland, Downing Street has said.

The move came after the Police Service of Northern Ireland (PSNI) offered a new assessment of Provisional IRA activity stating that aspects of the terror organisation have gone away, its active service units do not exist any more and what remains fulfils a radically different purpose than during the Troubles.

Both the Irish Government and the Democratic Unionists support a new form of paramilitary monitoring of the ceasefires.

The breakdown in relations at Stormont reached a new low after the killing of former IRA member father-of-nine Kevin McGuigan, allegedly by former terror associates.

That murder earlier this summer caused political uproar after PSNI chief constable George Hamilton said the IRA - which was supposed to have gone away a decade ago - still exists for peaceful purposes and the shooting was carried out by individual PIRA members but not sanctioned at a senior level.